GORY MCILROY: Rory McIlroy was one of several players who could not overcome the Olympic Club’s difficult conditions, leaving big-name pros, including world No. 1 Luke Donald, heading home from the U.S. Open early.Reuters; Getty Images (inset)

(
)

SAN FRANCISCO — For every action there is a reaction.

Rory McIlroy’s record-shattering 16-under-par performance en route to winning last year U.S. Open at Congressional was an action.

The reaction has been the USGA’s diabolical course setup for this year’s Open at Olympic Club. The result has been a good bit of carnage among the world’s best players.

Consider McIlroy, who took his share of lumps this week trying to defend his title, shooting an opening-round 77, followed by a 73 yesterday and a missed the cut at 10-over par.

Consider Luke Donald, the world’s No. 1 ranked player who was a popular pick by many to conquer Olympic this week and capture his first major. He shot an opening-round 79 and followed that with a 72 yesterday to leave the grounds as meekly as he’s competed in major championships during his career.

Donald, McIlroy and Westwood, the top three players in the world rankings, played the first two rounds together and finished a combined 26-over par with only Westwood surviving the cut.

Phil Mickelson, the five-time U.S. Open runner-up? He lost a ball on his first tee shot of the day Thursday and staggered to an opening-round 76, though he recovered to make the cut yesterday after shooting a 71.

Dustin Johnson, last week’s winner in Memphis and a popular pick to win this week, finished 9-over par and missed the cut.

Even some players who performed well on Thursday and appeared on their way to success, were overwhelmed by Olympic yesterday. Nick Watney, who had the shot of the day Thursday en route to a 1-under 69, followed that with a 5-over 75 yesterday.

“It’s kind of like a boxing match,’’ Watney said. “The course definitely won this round against me.’’

Blame it on McIlroy. Watney said he expected the USGA to respond to McIlroy’s assault on Congressional.

“I think we all kind of knew that the USGA was going to come out firing this year, and they haven’t disappointed,’’ Watney said.

Mike Davis, the USGA executive director who has final say in the course set-up, sounded delighted by the pain Olympic has doled out.

“It has played really the way we want a championship course to play,’’ Davis said. “It certainly was a good test of golf. It tested virtually every part of their game.’’

Asked if top players struggling is what golf fans want to see, Tom O’Toole, the chairman of the USGA championship committee, said, “I think the concept of trying to test the greatest players in the world might not be particularly spectator-oriented to some people. This has long been a brand of the USGA to be golf’s toughest test and require the players to use both mental and physical capabilities.

“That’s what makes the U.S. Open so unique. That’s what the USGA has built our brand on and we would continue to have that difficult examination. Some are traversing that and others are not.’’